1. Field of the Invention
This invention relates to improvements in lighter-than-air aircraft and more specifically to improvements in the deflating valve and the lift control structure for hot air balloons.
2. Description of the Prior Art
The need for a valve in the upper portion of a lighter-than-air (LTA) aircraft is well recognized to permit the rapid removal of the inflating and or lifting gas from the aircraft. This is desirable to avoid serious injury when landing a hot air balloon in the wind. After the balloon touches the ground the wind will drag the gondola if the top cannot be opened to allow the wind to force the lifting gas from the balloon envelope. It is at times necessary, and therefore desirable to close the opening after it is once opened to permit the balloon to contain and again fill with hot air before it has been collapsed. The valve must therefore be structured to close by air pressure when the opening cable is released. This is done only by the pressure of the escaping gas.
Prior known and available deflating or exhaust valves have included a circular panel sewn partially about the reinforcing or load tape sewn about the opening and this panel is otherwise sealed by a releasable fastening tape around the remainder of the opening. The fastening tape is typically hook and loop tape constructed of polymeric material. This valve is opened by a deflation strap attached to the panel diametrically opposite the sewn area and extending therefrom through a ring on the balloon envelope down to the gondola. After it is once pulled the panel could not close the opening because the air pressure folds it so it would not fill the opening to seal it. Further, this valve, during operation with the panel fully sealed, allowed the gas to leak through the polymeric hooks and loops. In a hot air balloon this gas is at a temperature of about 275.degree. F. which has a deleterious effect on the hooks and loops, degrading their holding strength. After as few as fifty hours of flight this hot gas substantially destroys the seal and little force, e.g. only 10 lbs of pull as opposed to 50 lbs when new, is ncessary to open the valve. With the holding capability of the hook and loops lost, tops have been known to be opened by the weight of the deflation strap, comprising a cable terminating in a strap on the lower end. Improvement on this valve is afforded by the present invention.
Another prior art valve is known as the parachute valve. This valve comprises a panel about twenty feet in diameter and located at the very inner apex of the balloon envelope. Spaced cords or lines from perimeter points on the panel are joined at a lower point to a single release or control line. The lines from the perimeter also extend to sewn points on the inner envelope to avoid displacement of the panel from the opening in the balloon. When the control line is pulled the panel is drawn from the opening allowing gas to escape through the opening. The gas will let the envelope reseal the opening when the control line is released. This valve relies entirely on gas pressure and has no mechanical securing system.
Control valves for adjusting the height of a balloon by releasing air is illustrated in U.S. Pat. No. 3,860,201, issued Jan. 14, 1975, to Ralph H. Hall.
The present invention affords a new method of deflating the balloon temporarily to let the balloon collapse and seek a lower altitude.